Device for introducing material into a degassing vessel for steel



INVENTOR Feb. 24, 1970 K. RUTTIGER DEVICE FOR INTRODUCING MATERIAL INTO A DEGASSING VESSEL FOR STEEL Filed Aug. 8, 1967 United States Patent 3,497,196 DEVICE FOR INTRODUCING MATERIAL INTO A DEGASSING VESSEL FOR STEEL Karl Ruttiger, Dortmund, Germany, assignor to Dortmund-Horder Huttenunion Aktiengesellschaft, Dortmund, Germany Filed Aug. 8, 1967, Ser. No. 659,206 Claims priority, application Germany, Aug. 10, 1966, D 50,806 Int. Cl. C21c 7/00, /42

US. Cl. 266-34 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the introduction of additives into steel melts contained in degassing vessels.

In one, known process for degassing steel, the steel is introduced into a degassing vessel 'which is then evacuated, and after being degassed the steel leaves the degassing vessel through an outlet connection. Continuous flow and pan degassing processes are also known.

In the case of steels which have to be not only degased but also de-oxidised or alloyed under vacuum, the degassing vessel has, up till now, been equipped with vacuum locks so that the necessary additives can be introduced into the degassing vessel without breaking the vacuum. The disadvantage of these known vacuum locks is that the additives can be added to the vacuum vessel through the lock only when cold. The cooling effect of the additives is intensified when, as is often the case, the process of solution in the melt is endothermic. Since the temperature of the melt must be maintained above an acceptable minimum, the quantity of alloying material and/ or de-oxidising agent that can be added is limited.

In accordance with this invention this disadvantage is overcome by a device for introducing material into a degassing vessel for steel, the vessel being arranged to be connected in use to a vacuum pipe, the device comprising a chamber for containing a reservoir of the material and having means for heating the reservoir of material, a siphon outlet which leads from the chamber and which is arranged to be connected in use to a degassing vessel, and a three way valve, one way of which communicates with the chamber, a second way of which is arranged to communicate with the vacuum pipe and a third way of which is arranged to communicate with a source of gas under pressure, whereby, with a reservoir of liquid material in the chamber, if the valve is, in use, changed from a first position, in which its first and second ways are in communication with one another, to a second position, in which its first and third ways are in communication with one another, gas is admitted to the chamber to increase the pressure in the chamber above that in the vessel so that at least some of the material in the chamber is expelled through the siphon outlet into the vessel.

The device thus enables solid or liquid substances to be introduced into the melt in the degassing vessel with- 3,497,196 Patented Feb. 24, 1970 out causing any significant loss of temperature and they can therefore be introduced in unlimited quantities.

The means for heating the material in the chamber is most conveniently an induction coil surrounding the chamber.

Preferably the device includes means for metering the quantity of gas admitted to the chamber in use when the valve is in the second position so that a predetermined quantity of the material in the chamber is transferred through the siphon outlet into the degassing vessel. The treatment substances can then be introduced into the degassing vessel, either continuously or in portions in precisely metered quantities.

A further advantage of the device according to the invention is that the substances are themselves already degassed by the vacuum in the chamber before entering the melt, and therefore their introduction does not disturb the degassing process of the steel melt.

One example of a device according to the invention is illustrated in the accompanying drawing which is a vertical section.

In the drawing, a feed chamber 1 is equipped with a siphon outlet 2 which leads through a gravity pipe 3 into, for example, a degassing vessel 4, in which portions of steel are degassed. The degassing vessel 4 is evacuated through a vacuum pipe 5, to which the feed chamber 1 is also connected by a pipe 6 and a three-way valve 7. The three way valve 7 is also connected to an inlet pipe 10 for air or other gas which enables the pressure in the feed chamber 1 to be increased. A metering means 11 communicates with inlet pipe 10 to meter the air or other gas drawn into the feed chamber 1. The feed chamber 1 is preferably surrounded by an electric induction coil 8, to allow heating up of the contents of the feed chamber. The fact that the feed chamber can be heated allows the additives 9 to be introduced in the solid or liquid state. If the additives are present in the feed chamber 1 as solids they can be melted by switching on the induction coil 8, or by activating some other heating device, for example graphite rod heaters, and in this way brought up to the temperature of the melt in the degassing vessel 4.

The operation of the device is as follows. After the additives 9 have been introduced into the feed chamber 1, the degassing is begun by evacuating the degassing vessel 4 and the feed chamber 1 through the two pipes 5 and 6. As soon as the additives 9 have been brought up to the temperature of the melt in the degassing vessel 4, the pressure in the feed chamber 1 over the molten additives 9 is increased, expelling the molten additives 9 into the degassing vessel 4. The pressure is increased in the feed vessel 1 by operating the three-way valve 7, so as to close the vacuum line 6 and open the gas connection 10. The quantity of additives expelled through the siphon 2 and through the gravity pipe 3 into the degassing vessel 4 is determined by the pressure increase in the feed chamber, depending on the internal diameter of the pipe connection 10 and the duration of opening of the three-way valve 7. In this way the quantity of additives introduced into the melt in the degassing vessel can be precisely controlled, and can also be measured for example by means of a liquid level gauge mounted on the feed chamber 1.

I claim:

1. In combination, a degassing vessel for steel and a device for introducing material into the vessel, said device comprising a surrounding wall defining a chamber, means for heating material disposed therein, a siphon outlet from said chamber, a pipe leading from said chamber and a three-way valve in said pipe whereby said pipe may be connected to a vacuum pipe in a first position of said valve and to a gas supply pipe in a second position of said valve, means connecting said siphon outlet to said vessel, a vacuum pipe, means operatively connecting said vessel to said vacuum pipe, and means connecting said valve in said first position thereof to said vacuum pipe.

2. A device according to claim 1, wherein said means for heating said material disposed Within said chamber comprises an electric induction coil.

3. A device according to claim 1, including metering means communicating With said pipe in said second position of said valve and adapted to meter gas drawn into said chamber from said gas supply pipe.

References Cited UNITED STATES PATENTS Newsome 164-155 Holz 164--254X Booth et a1 266-34 X US. Cl. X.R. 

